Journal of Horticulture
Din, et al., J Horticulture 2015, 2:3
http://dx.doi.org/10.4172/2376-0354.1000147
Research Article
Open Access
Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of
Temperature on Plant Dormancy and Growth
Gregory Yom Din1,2*, Menashe Cohen3 and Rina Kamenetsky4
1Open
University of Israel, Raanana, Israel
2Faculty
of Exact Sciences, Tel Aviv University, Tel Aviv, Israel
3Northern
4Institute
R&D, Migal, P.O. Box 831 Kiryat Shmona 11016, Israel
of Plant Science, Agricultural Research Organization, Volcani Center, Bet Dagan 50250, Israel
*Corresponding
author: Gregory Yom Din, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, Israel, Tel: 972-545599329, 972-46964932; E-mail:
[email protected]
Rec date: Apr 10, 2015; Acc date: June 24, 2015; Pub date: June 27, 2015
Copyright: © 2015 Din GY, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and source are credited.
Abstract
This article introduces the first database for developmental parameters of the herbaceous peony cultivated in a
warm climate region. Data on the effect of temperature during dormancy and growth parameters are presented for
2,232 plants of two commercial cultivars exposed to 14 different temperature regimes: 15-18 dates of dormancy
release for each regime and 10 weekly measurements of 6 growth parameters for each plant. Diversity of
developmental response was examined with a Tukey test. The efficacy of the database for the regulation of the
developmental processes and production ability is demonstrated with numerous examples of estimated growth rate
of stems. The sigmoid nature of the growth curves is noted. The database could be used for research on plant
physiology of peony and other geophytes, as well as for the prediction of effective commercial flower production.
The database is available at http://www.mop-zafon.org.il/files/DB18_Sept_2014.xlsx.
Keywords: Database; Peony; Dormancy; Phenology; Sigmoid
growth; Flower production; Profitability
Introduction
Peonies are popular and well-known ornamental plants commonly
grown in temperate, cold-winter climatic regions [1]. As in many
geophyte species, a perennial underground crown (metamorphosed
shoot) serves for the accumulation of storage products and for plant
renewal. Numerous buds form on the surface of the crown and near
the bases of aboveground stems, and after sprouting, they develop into
monocarpic shoots with several leaves and terminal and auxiliary
flowers [2]. Similar to many other perennial plants originating from
temperate climate regions, during their annual growth cycle, peonies
undergo periods of considerable environmental changes. Progressive
adaptation to the climatic cycle led to the development of special
growth patterns to escape unfavorable periods and to resume plant
growth in the appropriate season. In the fall, when temperatures
decrease, peony plants enter a dormancy period defined as "a
temporary suspension of visible growth" [3]. Once dormancy has been
initiated, a prolonged period of chilling is needed to break it but cold
requirements are cultivar-specific [4,5].
In temperate northern hemisphere regions, peonies flower in MayJuly. Following a tough winter and a cold spring, the peony season can
be delayed up to three weeks. As a result ofa decrease in
supplyanddespite the possible price increase, farmers profitsin these
yearsare reduced [6]. Recently, the possibility of peony cultivation in
regions having a warm climate was reported [7,8]. In addition, in
colder regions peonies can be forced towards early production of cut
flowers under greenhouse conditions [9-11]. Cultivation of peonies
under warmer conditions accelerates the flowering process and may
J Horticulture
ISSN:2376-0354 Horticulture, an open access journal
provide an excellent early-market niche. However, an insufficient
chilling period and not low enough soil temperatures will cause a slow
dormancy release, poor stem elongation, and often flower abortions.
Climate change may exacerbate these effects as soil temperature
integrates all processes occurring at and above the soil surface [12]. In
order to enhance the early forcing and improve the profitability of
peonies growing under warmer conditions, in-depth knowledge of
temperature requirements during various stages of its annual growing
cycle is required.
In a previous study, the key relationships between chilling regimes
and dormancy release, peony stem elongation and flowering were
studied. The chilling requirements for dormancy release were
determined in field-grown peony plants by exposing them to ambient
winter-cold weather in northern Israel (8-10°C night, 16-26°C day,
average ca. 17°C from November to February). The greenhouses were
covered with plastic sheets at different dates, following the
accumulation of chill units calculated according to Fishman et al. [12]
and Erez et al. [13]. Flowering occurred two months following
dormancy release [14].
For container-grown and artificially cooled peonies, chilling
regimes of 2°C for 60 days ('Sarah Bernhard', 14) or 1-7°C for 3-12
weeks (‘Coral Sunset’, ‘Monsieur Jules Elie’, ‘Sarah Bernhardt’;) were
identified [4]. The time until sprouting upon the completion of
chilling treatments decreased with an increase in the duration of
chilling treatments [7]. In Chinese varieties, stem height, flower size
and flowering rate were also positively affected by chilling [15].
However, none of these studies provided a comprehensive database
on the environmental regulation of peony development that would: a)
enable following up single plants in different physiological stages; b) be
Volume 2 • Issue 3 • 1000147
Citation:
Din GY, Cohen M, Kamenetsky R (2015) Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of Temperature
on Plant Dormancy and Growth. J Horticulture 2: 147. doi:10.4172/2376-0354.1000147
Page 2 of 7
large enough for statistical analysis; and c) be available for the
scientific community.
flowering) were collected. Peony cultivars ‘Sarah Bernhardt’ (SB) and
'Duchesse de Nemours' (DN) were used.
Many reported greenhouse experiments for testing the effects of
climatic conditions on plant development accounted for only a
relatively small number of plants. The effect of environmental factors
on the growth of Oxalis pes-caprae, a geophyte from Mediterranean
regions, was studied on 80 plants grown in pots in a greenhouse [16].
The effect of day and night temperatures on the flowering of
Phalaenopsis orchids was studied on 240 plants, also grown in a
greenhouse, for different day and night temperature regimes [17].
Similarly, for fruit trees, usually the data of only a few dozen plants
were available for determining dormancy conditions, estimating
chilling models and comparing dormancy adaptation strategies
[18,19].
The purpose of this study is threefold: (1) to introduce the database
design that meets the need of the plant level research of the peony
growth processes related to dormancy and its release; (2) to represent a
collection of data on dormancy release requirements and stem
elongation for herbaceous peony during the production cycle in the
Mediterranean region, and make it available for other researchers to
use; (3) to examine the diversity of these data collected for different
chilling treatments and growth techniques, and to illustrate their
utility for research on plant growth.
We sought to address the following specific research issues:
1.
2.
3.
4.
The design and implementation of the data collection: a) in the
stage of winter dormancy (temperature data); and b) following
dormancy release, and during the stages of sprouting and stem
elongation (phenological data).
Development of a plant-level database describing interactions
between environmental conditions and plant development.
Statistical analysis of treatment differentiation.
Demonstration of the effectiveness of the database for studying
and predicting physiological responses of peonies to various
environmental conditions during dormancy and following its
release.
Addressing the above-formulated issues of the study became
possible by using herbaceous peony as a subject of research. The study
used a large sample of 2,232 plants of two different cultivars under
diverse conditions of cold storage chambers, open fields and
greenhouses – a total of 14 treatments and plant growth techniques.
We collected a large amount of data during dormancy and following
its release at the plant level using electronic devices and visual
observation. Using these data, we created a database in Excel for
Windows accessible to other researchers.
To the best of our knowledge, this is the first reported database at
the plant level for peony in particular and for geophytes in general.
The database is available at http:// www.mop-zafon.org.il/files/
DB18_Sept_2014.xlsx.
Treatments and Database Design: Preliminary Analysis
of the Data Collected
Figure 1: Annual cycle of herbaceous peony. A: In autumn, aboveground stems wilt and the plant enters dormancy, which is released
following a cold period. B: Sprouting of underground buds, stem
elongation and flowering occur in spring. C: After flowering, stems
and green leaves continue to function and translocate
photosysntetic products to the developing underground organs
until wilting in autumn.
In March 2011, three-year old plants grown at the AvneiEitan
experimental station (Northern R&D, Israel) were divided into
propagation units. One thousand four hundred and forty units were
planted in natural soil in tunnels in an open area. In October 2012,
different chilling regimes for plants in tunnels were induced using
thermal reflecting sheets and soil wetting. In addition, 792 plants were
planted in 10 L containers and placed either in the tunnels or in
cooling chambers at constant temperatures (for details, see Appendix
A). Six containerized plants from each treatment were transferred to a
greenhouse every week from the end of October 2012 to the end of
February 2013. For peonies planted in natural soil, dormancy was
broken at different dates by covering the tunnels with polyethylene
sheets. Following dormancy release, six phenological parameters were
measured once a week for each plant. Multiple chilling regimes and
growth techniques, as well as calendar dates of the transition from
phase A to phase B (Figure 1) enabled collecting diverse data on winter
dormancy and spring phenology of peony.
Database design
The data collected were organized in an Excel database. During the
dormancy period, air and soil temperatures were transferred from the
temperature accumulation stations (Appendix A) into the database
Excel file. In this article, soil temperatures at 5 cm depth were used for
exemplary analyses and illustrations.
Overview of the experimental design
For each treatment, the collected temperature data enabled
calculating coefficients of temperature variations and chill units.
Winter dormancy, bud sprouting and stem elongation present the
consecutive phases of the annual cycle of peony (Figure 1). Data from
phases A (dormancy) and B (sprouting, stem elongation and
A coefficient Tvar(k) of temperature variation from the beginning
of the treatment to the end of week k was calculated as a sum of
absolute values of temperature differences:
J Horticulture
ISSN:2376-0354 Horticulture, an open access journal
Volume 2 • Issue 3 • 1000147
Citation:
Din GY, Cohen M, Kamenetsky R (2015) Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of Temperature
on Plant Dormancy and Growth. J Horticulture 2: 147. doi:10.4172/2376-0354.1000147
Page 3 of 7
Tv a r k =
Nk
In fact, for every week of the dormancy phase, cumulative chill-heat
units were calculated.
i =1
The database includes the following data tables, each of them stored
in a separate spreadsheet:
∑ a bs t i +1 − t i
i+1t i kkrT r lT r u
Tr k =
N k t i ≤T u
r
∑ ∑
i =1 t ≥T l
i r
•
ti
Chill units are used in numerous chilling models of dormancy for
fruit trees. A detailed survey of various modifications of these models
explaining the effect of chilling and warm temperatures accumulated
in different temperature ranges for specific trees and climate can be
found in the study by Luedeling, et al. [19]. Contrary to chilling
models for fruit trees based on air temperatures, soil temperatures in
our study measured at a depth of 5 cm were used for calculating chill
units. In addition, the chill units were calculated for every week k of
the dormancy phase (maximal k equals 15 or 18 for different
treatments in Supplementary Table A3), and not for the entire winter
period, as in previously published reports. In our database, chilling
units were calculated for 13 temperature ranges – from lower than 3°C
to higher than 27°C.
•
•
•
•
“Weeks” – an auxiliary table for translating 10-minute intervals
into numbers of weeks
“Temperatures” – records by 10-minute intervals
“Phenology” – by week intervals
“Chill-Heat units” – accumulated temperatures for 13 temperature
ranges and temperature variation – all these indices were
accumulated by weeks of dormancy. This table relates to the
Temperatures and Weeks tables (Figure 2).
“Plant History” – the main output of the database that enables
describing phases of winter dormancy, sprouting (dormancy
release) and stem elongation. For each plant, the corresponding
row of this table relates to the temperatures in different weeks of
its dormancy (from the Chill-Heat units table) and to its
phenological data (from the Phenology table) (Figure 2).
Figure 2: The flow-chart of the database.
The Plant History table includes 28 fields relating to temperature
ranges and phenological stages of plant development (Table 1).
Code
Definition
ID
Identification number of the measurement
Date
Data of the measurement of phenological data
Phenology
Treatment
Treatment number from 1 to 10
ditto
Release
Week number of the dormancy release
ditto
J Horticulture
ISSN:2376-0354 Horticulture, an open access journal
Table - data source
Volume 2 • Issue 3 • 1000147
Citation:
Din GY, Cohen M, Kamenetsky R (2015) Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of Temperature
on Plant Dormancy and Growth. J Horticulture 2: 147. doi:10.4172/2376-0354.1000147
Page 4 of 7
Week
Week number of the measurement of phenological data
Weeks
Plot
Plot number for plants grown in natural soil
Phenology
Variety
Name of the variety
ditto
Plant
Plant number in the same measurement: from 1 to 6 for plants in containers, from 1 to 12 for plants in ditto
natural soil
T51
Temperature at 5 cm depth, in the range < 3°C
Chill-Heat units
T52
In the range (3, 5)
ditto
T53
In the range (5, 7)
ditto
T54
In the range (7, 9)
ditto
T55
In the range (9, 11)
ditto
T56
In the range (11, 13)
ditto
T57
In the range (13, 15)
ditto
T58
In the range (15, 17)
ditto
T59
In the range (17, 19)
ditto
T510
In the range (19, 21)
ditto
T511
In the range (21, 24)
ditto
T512
In the range (24, 27)
ditto
T513
In the range > 27
ditto
Tvar
Coefficient of temperature variations
ditto
Sprout
Number of sprouts
Phenology
Height
Maximal height of sprouts, cm
ditto
Buds
Number of buds
ditto
Flowers
Number of flowers
ditto
Cutting
Cut flowers
ditto
Abortion
Buds abortion
ditto
Table 1: Fields of the plant history table.
The database is designed in MS Excel 2010 using spreadsheet
functions VLOOKUP, COUNTIFS, SUMIF for combining data that
relate to the same plant collected in different phases and weeks of
measurement. Such organization of the output data can be convenient
for mathematical modeling of geophytes development.
The database structure and relationships between the tables are
shown in Figure 2. The Plant History table relates to the Chill-Heat
units and Phenology tables. Each row in the Plant History table is
generated for a given treatment, week of dormancy release and plant
number, and comprises phenological data for all the weeks of the
records.
Preliminary analysis of data collected
Analysis of treatment differentiation: For the data collected in both
phases of plant development, the overall difference between treatments
can be analyzed using the one-way analysis of variance (ANOVA).
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ISSN:2376-0354 Horticulture, an open access journal
Then, in the case of positive results of this test (significant differences),
the Tukey post-hoc test based on a multiple comparison procedure
can be conducted for discriminating between treatments and dividing
them into statistically homogeneous groups. Using records of the
Chill-Heat units and Plant History tables, a comparison can be
performed for each Chill-Heat unit and phenological index.
Analysis of stem elongation:We used sigmoid growth curves (the
logistic curve and its generalizations) for the approximation of growth
of peony stems. Richards [20] suggested that these functions could be
useful for the empirical description of plant growth.
A specific growth rate SG of peony stems was defined as the rate of
growth divided by stem height:
1 dH
SG = H dt
Where H is the stem height and t is time (in weeks).
Volume 2 • Issue 3 • 1000147
Citation:
Din GY, Cohen M, Kamenetsky R (2015) Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of Temperature
on Plant Dormancy and Growth. J Horticulture 2: 147. doi:10.4172/2376-0354.1000147
Page 5 of 7
Under these assumptions and using the techniques first presented
by Kaufmann [21], the following estimate of specific growth SG for the
growth curves can be derived:
H2
−1
H2 −H1 H1
SG = H dt ≈
=
≈
Δt
H 1 ⋅ Δt
containers transferred to a greenhouse (treatments 1, 4-10) were
appended to the Phenology table. In treatments 1-6, the same data
were collected for the plants grown in natural soil. A section from the
outcome of the Plant History table is shown in Figure 3.
1 dH
w hen H 2 is c lose to H 1
ln
H2
H1
lnH 2 −lnH 1
=
Δt
Δt
(4)
Where H1 is a stem height at the beginning of the time interval (Δt=
1 week), and H2 is the height at the end of the time interval.
The growth rate (general) G of stems for each measurement was
calculated as follows:
H
G = du r a tionof stem e long a tion
Results
Statistical analyses were conducted using SPSS (2011) and
Microsoft Excel [22].
Once a week during the dormancy phase (20 weeks from the middle
of October to the middle of March, under conditions in the tunnels),
1,008 records of 10-minute temperature data from each treatment
were appended to the Temperatures table. The cumulative sums of
temperature and coefficient of temperature variation were then
calculated for the Chill-Heat units table, as shown in formulas (1) and
(2). Following dormancy release, phenological parameters were
recorded once a week during 15 weeks from the beginning of February
to the middle of May 2013. Data on the number of sprouting buds and
maximal length of stems and other phenological indices for plants of
Figure 3: A section from the Plant History table. The field “plant” in
the first row is equal to 1, the field “treatment” is equal to 8, and the
field “release” is equal to 844. This means that the data in this row
relate to treatment 8 and to plant 1 from the six plants transfered to
the greenhouse at week 44. The field “week” is equal to 5. This is the
number of the calendar week corresponding to the “date” 3/2/2013
of the measurement of phenological data.
A statistical summary of the data from both phases is presented in
Appendix B, Table A4. The ANOVA test (not presented here) showed
significant differences between the treatments for most indices of the
calculated chill-heat units, temperature variation, number of sprouts
and stem height. An example of distribution of one of these indices mean height of stems - by treatments, and its standard errors is shown
in Figure 4. This index ranged from 5.1 cm and 6.4 cm in treatments 9
and 5, respectively, to 35.8 cm in treatment 7 (and was close to zero in
treatment 10 in a cooling chamber with a constant temperature of
20C).
Figure 4: Mean height of peony stems recorded in various temperature treatments (the treatments are described in Appendix A). Each error
bar represents the standard error of all measurements for various plants and weeks in this treatment.
Application of the Tukey test (significance level 5%) enabled
examining treatment differentiation by identifying homogeneous
groups of treatments for each of the aforementioned indices of
temperature and phenology. For almost all of the indices, the number
of homogeneous groups of treatments varied from 4 to 8 (from 10),
most of them non-overlapping. Not one pair of treatments belonged to
the same homogeneous groups for all temperature indices. A similar
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ISSN:2376-0354 Horticulture, an open access journal
result was obtained for phenology indices of number of sprouts and
stem height. These results show a significant treatment difference by
temperature in the dormancy phase and by phenological indices in the
stem elongation phase (Appendix C). This means that the temperature
regimes and developmental parameters differed significantly for plants
in each pair of treatments.
Volume 2 • Issue 3 • 1000147
Citation:
Din GY, Cohen M, Kamenetsky R (2015) Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of Temperature
on Plant Dormancy and Growth. J Horticulture 2: 147. doi:10.4172/2376-0354.1000147
Page 6 of 7
To demonstrate the effectiveness of the database for studying peony
phenology in the stem elongation phase, a specific growth rate SG of
peony stems was estimated using formula (4) and based on records
from the Plant History table. For this purpose, we selected examples of
plants for which the sigmoid behavior of their growth curves was
expressed visually (Figure 5).
Figure 5: Samples of growth patterns of peony stems based on
database records. The 3-digit code of the treatment means the
number of treatment (first digit) and week number of the
dormancy release (last two digits). For example, code 602 means
treatment 6 and that the plant was transferred to the greenhouse in
week 2 (Jan. 7-13, 2013).
This was correct for many plants from treatments 7, 8, 9 exposed to
constant temperatures (2C, 6C, 10C, respectively) in cooling
chambers. For treatment 7, for example, chilling for 2 weeks was
enough for the sigmoid growth curve of plant 4 (treatment code 744).
On the other hand, for the plants grown in natural soil, this elongation
pattern was recorded for only some of the plants after 10 weeks of
dormancy (treatment code 152) or even longer: treatment codes 101
and 501 – 11 weeks; treatment code 602 – 12 weeks; treatment code
404 – 14 weeks (Figure 5).
For each of the selected plants, specific growth rates SG for every
week following dormancy release were calculated and averaged
throughout the stem elongation period. Average specific growth rates
SGav are shown for all plants in Figure 5. For certain plants, these
average rates varied from 40% to 87%.
For each treatment, growth rate of stems G was calculated for each
plant and averaged over all plants for the treatment and weeks of the
stem elongation phase (Table 2). This index is in good agreement with
the stem height distribution shown in Figure 5 and in the last column
of Table 2 (the coefficient of correlation r=0.75 is statistically highly
significant).
Discussion
In this study, we present the database developed for studying the
cultivation of herbaceous peony in a warm climate region with a
deficiency of low temperatures for dormancy release. In total, 2,232
plants exposed to 14 temperature regimes were used as a source of the
experimental data. The 10-minute measurements of soil temperature
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ISSN:2376-0354 Horticulture, an open access journal
were collected in the database during the phase of winter dormancy
prior to sprouting.
Treatment
Average
95%
Growth Rate G, Confidence
cm/week
Interval for G
Mean Height, cm (the
entire
measurement
period)
1
1.36
±0.145
9.0
2
4.7
±0.242
15.9
3
3.98
±0.169
20.4
4
1.32
±0.175
9.9
5
1.06
±0.136
6.5
6
0.73
±0.061
17.8
7
4.2
±0.150
35.8
8
3.08
±0.160
23.2
9
1.01
±0.122
5.1
10
0.14
±0.089
0.3
Table 2: Growth rate of stems in various temperature treatments.
In the bud sprouting, stem elongation and flowering phase,
phenological data for each plant studied were collected once a week
(from 9 to 11 measurements for different treatments).
Overall, the database includes close to 600,000 values of
temperature and more than 90,000 values of phenological data relating
to specific plants for various treatments, dates of dormancy release and
phenological records. This database and its design followed the design
of the treatments and can be used for studying herbaceous peony and
other geophytes in warm climate regions. Further development of this
database will help to predict crop production processes on a
commercial scale.
Similar to many fruit trees, perennial herbaceous plants, geophytes,
as well as peony plants require a certain amount of cold, usually
presented as “cold units,” for dormancy release. However, in studying
peony, unlike trees, air temperature records from regional
meteorological stations are not sufficient. The renewal buds of peony
are located underground, and therefore apical meristems and roots are
sensing soil temperature.
The approach used in the design of the database presented is in line
with the results of many other studies on plant dormancy. Using soil
temperatures measured in our database is similar to a certain extent to
using air temperatures in chilling models for fruit trees dormancy:
chill-heat units used in the Utah model and its modifications [23,24].
In our study, calculating chill-heat units for 13 ranges of temperatures
(from lower than 3C to higher than 27C for a winter climate at the
AvneiEitan station) enable modeling the negative effect of high
temperatures similarly to dormancy of fruit trees in the studies of Erez
[25] and Guerriero et al. [26]. The other opportunity could be using
hourly data of minimum and maximum temperatures during the
dormancy period (e.g., models from the studies of Aron [27], Orlandi
et al. [28], Miranda et al. [29]. The temperature variability index
calculated in our database can be useful for the future modeling of
peony phenophases as it follows from the study by Eppich et al. [30] of
climatic effects on the phenology of geophytes.
Volume 2 • Issue 3 • 1000147
Citation:
Din GY, Cohen M, Kamenetsky R (2015) Database for Herbaceous Peony Cultivated in Warm Climate Regions: Effects of Temperature
on Plant Dormancy and Growth. J Horticulture 2: 147. doi:10.4172/2376-0354.1000147
Page 7 of 7
Using the database and the Tukey statistical test, we showed
significantly different effects of temperature regimes on dormancy
release for plants grown in containers (both in tunnels and in cooling
chambers), as well as in natural soil (in tunnels). Phenological indices
in the stem elongation phase were also significantly different among
the various treatments. To enable future statistical estimation of the
relationships between the two physiological phases of peony growth,
the records relating to various treatments, plants and phases were
organized in the combined Plant History table, which included more
than 15,100 data records.
11.
12.
13.
14.
15.
The practical value of the database presented for research purposes
is the possible prediction of flower production in warm climate
regions, as well as the use of greenhouse forcing. Further analysis of
data accumulated in this research will enable the development of
practical recommendations for artificial chilling treatments and
growth techniques in commercial peony production. Therefore, the
database that combines data from different physiological phases of a
flower plant could be useful for developing decision-making tools
aimed at ensuring the majority of a crop to be ready for harvest by a
target date. It can help to increase the profitability of the crop, which
depends on the date of sale and the length of the stems. Such a tool for
an Easter lily crop (another geophyte flower with considerable
economic potential) was developed by Fisher and Lieth [31].
20.
Acknowledgments
21.
The authors gratefully acknowledge Dr. Raffi Stern and Professor
Moshe Reuveni for their professional advice.
22.
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